Removal and analysis of materials collected in filters provides important information useful to ascertain or diagnose the history or operating state of the system with which the filters are used.
Examples to illustrate the broad applicability of filter retentate analysis include filters used in commercial and industrial processes and applications. Analysis of the material collected on the filters and comparison with known standards or reference materials provides information on the state of the system generating the retentate. In this manner, information may be obtained to discern the operating history or changes in operation of the system generating the retentate during the period in which the filter is in service.
One particular example includes particulate filters, such as diesel particulate filters or gasoline particulate filters, but any filter or retentate collection media or system may be used. In the case of a particulate filter installed in the exhaust of an engine or other system (plant or process) generating retentate, the filter captures and collects retentate produced by the system. While effective at capturing retentate, the use of filters also has some disadvantages.
First, the filter may mask or hide signs of engine, plant, or process malfunctions or failures. For example, leaks of fluids, gases, or the generation of other emissions or effluent from the engine, plant, or process which otherwise may be directly visible to the operator may also be collected on the filter. In the case of an exhaust particulate filter, signs of engine malfunctions such as blue, black, or white smoke exiting the tailpipe may no longer be visible, as the smoke or vapors are captured on the filter.
Second, the accumulation of retentate generated as a result of a system malfunction, such as particles, liquids, or other components for which the filter was not intended, may also cause damage to the filter. In one example, an engine oil leak, coolant leak, or improper combustion may lead to the accumulation of coolant, oil, fuel, or high levels of soot on the exhaust particulate filter, which could adversely affect filter performance and service life, in addition to that of the engine, process, or plant.
In many cases, filters are periodically removed for cleaning or reconditioning so that they can be reused, rather then replaced. In many cases, the filter cleaning or reconditioning involves removal of the retentate from the filter. Common methods of filter cleaning involve the use of forced air to blow the retentate out of the filter, liquid-based cleaning or washing methods, thermal cleaning, the use of vibrations, and other related means. Most filter cleaning systems and processes further aggregate and collect the retentate removed form the filters in a bulk collection system, such as a liquid storage tank, dust collection system, and the like. The use of these conventional bulk cleaning processes has several drawbacks as well.
First, collection of the bulk retentate removed or cleaned from the filters in aggregate collection systems, such as a dust collection system or liquid storage tank, does not allow for the retentate to be uniquely identified or linked to the filter from which it was removed. Thus, any subsequent analysis of the retentate will not enable any useful diagnosis of the filter state or engine/equipment that generated the retentate, as all of the retentate is mixed together in the bulk collection system from various sources.
Second, cleaning methods which destroy, alter, or in any other way affect or modify the properties of the retentate, such as its characteristics, or physical or chemical properties, further preclude any meaningful analysis and diagnosis of the stat of the engine, equipment, plant, process, or filter from which the retentate originated.
Therefore, a retentate removal or collection system is desired, which would allow the retentate removed from a particular filter to be uniquely linked or identified by the filter from which it was removed. Note in some cases it may not be necessary to remove the retentate from the filter but rather to remove a small portion of the filter containing the retentate for analysis, or conduct the analysis of the retentate on the filter directly, without removing the retentate or altering the filter. In addition, it is highly desirable to avoid or minimize any changes to the retentate prior to the analysis.
Therefore, an improved process of collecting and analyzing retentate is needed, which will have considerable utility for a broad range of applications and fields of uses.